Aircraft with lift rotors

ABSTRACT

An aircraft having at least one horizontal engine unit and lift rotors disposed symmetrically with respect to the fuselage. Each of the rotor blades of the lift rotors includes a rotating drum for producing a lifting effect in an air current according to the Magnus effect. The drums are rotated by means of turbines driven by a jet of gas which is simultaneously utilized to produce the rotation of the lift rotors.

United States Patent Dietrich lDziallas Bremen, Germany July 241, 1970 Dec. 14, 11971 Verelnigte Flugteclmlsclle Werke-Fokken GmBH Bremen, Germany [72] Inventor [21 Appl. No. 22] Filed [45] Patented 73] Assignee [54] AIIRCRAFT WITH LIFT ROTORS 16 Claims, 7 Drawing Figs.

[52] 11.8. C1 2441/7 A [5 I 1 1364c 27/22 [50] Field of Search 244/7 7 A, 4

[56] References Cited UNITED STATES PATENTS 3,116,036 12/1963 Nichols 244/7 3,149,800 9/1964 Sintes et a1. 244/7 3,159,360 12/1964 Ryan et al 244/7 Primary Examiner-Trygve M. Blix Assistant Examiner-Carl A. Rutledge Artorney-Spencer & Kaye ABSTRACT: An aircraft having at least one horizontal engine unit and lift rotors disposed symmetrically with respect to the fuselage. Each of the rotor blades of the lift rotors includes a rotating drum for producing a lifting effect in an air current according to the Magnus effect. The drums are rotated by means of turbines driven by a jet of gas which is simultaneously utilized to produce the rotation ofthe lift rotors,

PATENIED um I 41971 SHEET 1 UP A lnven q r Dietrlich Dziullqs VATENTEBBEBMM 35271234 SHEET 3 BF 4 mvenmr: Dietrich Dziollas BY W a %w ATTORNEYS.

BACKGROUND OF THE INVENTION The present invention relates to an aircraft having at least one horizontal engine unit and lift rotors disposed symmetrically to its fuselage with the rotor blades of the lift rotor including rotating drums which produce a lifting effect in an air current according to the so-called Magnus effect.

The general use of rotating drums to produce a lifting force is known in the art. That is, it is known that it is possible to produce a lifting force in a translation current utilizing rotating drums according to the so-called Magnus effect. Although a lifting force produced in this manner is much greater than the lifting force of conventional wing profiles, this fact has not as yet been afforded any significant importance in the construction of aircraft.

It has been proposed to replace the rotor blades of helicopter rotors with rotating drums. For helicopters, how ever, the use of such arrangements results in great difficulties. These difi'rculties result mostly from the drive means for the drums since they require a substantial quantity of relatively expensive drive elements, such as shafts, couplings, gears, etc., in order to produce the high number of revolutions necessary to produce advantageous lifting values. Such lifting rotors have also been proposed for winged aircraft with the drums being selectively extended from or retracted into the aircraft. It was here the intention to release and drive the drums for vertical flight and to retract them into the rotor hub during forward flight, in order to provide more favorable aerodynamic conditions during forward flight. This construction, however, also requires expensive drive elements and accordingly lifting rotors have not as yet been used for aircraft due to the great expenditures involved.

SUMMARY OF THE INVENTION The present invention avoids the above-described drawbacks in that the rotating drums are driven by turbine stages which permit axial flowthrough and are driven by a stream or jet of gas. The jet of gas is discharged from the rotor to the outside, after passing through the turbine stages, through nozzle-type openings, so that the rotor hub is caused to rotate by the resulting thrust.

The present invention thus makes it possible to drive the drums as well as the rotor hub with a single jet of gas, which can be taken from an available horizontal engine unit of the aircraft so that no additional expenditures are here required, either.

According to a further feature of the present invention, the required lift during takeoff and landing of an aircraft is produced by means of the lifting rotors, and means are provided for maintaining the lifting rotors, during cruising flight when the wings provide the necessary lift, in a stopped position with the drums parallel to the aircraft fuselage so that the rotor blades including the drums form a low aerodynamic drag. It is here advisable to reduce the diameter of the drums with increasing distance from the axis of the rotor hub since this results in further improvements of the aerodynamic conditions during cruising.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of an aircraft with lifting rotors according to the invention.

FIG. 2 is a frontal view of the aircraft of FIG. 1.

FIG. 3 is a schematic sectional view of one embodiment ofa lifting rotor according to the invention.

FIG. 4 is a schematic side view of the lifting rotor according to FIG. 3 taken along the line 4-4 of FIG. 3.

FIG. 5 is a schematic sectional view of a modification of a lifting rotor of FIGS. 3 and 4.

FIG. 6 is a schematic sectional view of another embodiment ofa lifting rotor according to the invention.

FIG. 7 is a partial sectional view through a wingtip of the aircraft, e.g. as shown in FIG. 2, illustrating an embodiment of the detent mechanism for maintaining the lift rotor according to the invention in a desired position during cruising flight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. I, there is shown a perspective view of an aircraft having a fuselage l0 and two Wings 11. On the upper side of the outer ends of each of the Wings 11 there is disposed a lifting rotor l2. The lifting [rotors 12 each consist of a rotor hub 13 and a plurality of rotor blades 14, preferably two as shown, which are in the shape of drums. A frontal view of the aircraft of FIG. 1 is shown in FIG. 2. When the aircraft takes oh, the drums 14 as well as the rotor hubs 13 are caused to rotate by a jet or stream of gas in a :manner to be more fully explained below. Drums l4 rotate around axis 15 whereas the rotor hubs 113 simultaneously rotate around axis lllfiwhich is transverse to the axis 15. With the appropriate number of revolutions this causes a lift according to the so-called Magnus effect. When the aircraft is cruising, the lifting rotors 12 are preferably stopped so that the drums 14 are parallel to the fuselage 10 of the aircraft so that their aerodynamic drag is very low. During cruising flight, the forward thrust for the aircraft is provided by at least one and preferably two horizontal engine units which may be mounted either on the fuselage 10 or on the wings lll. For example, as indicated, two horizontal jet engines 17, one on either side of the fuselage, may be utilized.

A schematic diagram of one embodiment of a lifting rotor according to the present invention is shown in FIGS. 3 and 4. The rotor hub 13 comprises a pair of transversely arranged shafts 20, 21, which may, as indicated, he a single T-shaped shaft to which is securely fastened a T-shaped hollow pipe 25, 26, for example by means of supporting struts 27. The vertical shaft 20 is rotatably mounted by means of bearings (not shown) in the wing Ill, while the laterally extending shaft 2i extends beyond the lateral portions 26 of the T-shaped pipe 25, 26 and constitutes the mounting member for the blade portions of the rotor. The shaft 21, which serves as the force receiving element of the rotor, as well as the shaft 20, may, if desired, be constructed as hollow tubes or pipes so that they can be used as gas conduits.

Rotatably mounted on each end of shaft 21 by means of bearings 32, 32' is a drum 14 which is :in the form ofa hollow tube, which, as indicated, preferably has a constant diameter, i.e., a cylindrical shape. In order to drive the drums 14, each drum is provided with at least one gas turbine stage. Preferably, each drum I4 is provided with a pair of turbine stages 23, 23', one at each end of the drum 14 so that the turbine stages form the support for the drums on the shaft 21.

The outer end of each of the rotor blades is provided with a closing cap 22 which is securely fastened to the outer ends of the shaft 21, which ends extend somewhat beyond the drums 14. The closing caps 22 may, for example, be connected with the shafts 21 by means of supporting struts 28. The closing caps 22 are provided with guide vanes 52 and nozzle-type discharge openings 24 which face or open in a horizontal direction transverse to the axis 15 of the shaft 21. When the shaft 21 is constructed as a pipe and is used as gas conduit, the end thereof is preferably curved in the direction of the openings 24 in order to increase the efficiency of the rotor.

To drive the lifting rotor, a jet or stream of gas is utilized which preferably is taken from an available engine unit such as the units 17. This gas jet, which is indicated by arrows 29, is directed to the rotor via the transverse member 25 and then to the longitudinally extending members 26 of the rotor hub 13. The gas jet exiting from the hub I3 then travels through the first turbine stage 23, the drum l4, and the second turbine stage 23', causing each drum 14 to rotate, on its bearings 32, about the shaft 211, as indicated by arrow 30. After passing through the last turbine stage 23', the gas jet finally reaches the closing cap 22 wherein it is deflected due to the shape thereof to the nozzle-shaped discharge openings 24. Due to the recoil or thrust created by the gas leaving the rotor via the nozzle-type discharge openings 24, the rotor hub 13 is driven so that it rotatesin the direction of arrow 31 around axis 16 of shaft 20. Thus a single gas jet drives, without additional expenditures, the drums 14 as well as the rotor hub 13. By suitable adaptation of the relative rotational directions, as indicated, which can be varied by a change in turbine stages 23 or by a suitable arrangement of the nozzle-shaped discharge openings 24 on the opposite side of the closing caps 22, respectively, a lifting effect according to the so-called Magnus effect is produced.

With large lifting rotors the shafts 20, 21, which in this case are designed as tubes, can also be used to conduct the gas. The shaft 21 can be utilized to carry a hot gas jet whereas a cold gas jet is conducted through the remainder of the drums 14. It is also possible to interchange these gas jets or to mix them, and thus reduce the danger of icing.

FIG. shows a schematic sectional view of the lifting rotor according to the invention illustrating a modification of the mounting shown in FIGS. 3 and 4 for the drums 14. According to this modification metal rings designed to enhance the air flow through the lifting rotors are provided. These rings, which, as illustrated. preferably have walls in the shape of an air foil, consist of a stationary portion 35 which is fastened to the supporting struts 27 of the longitudinal members 26 of the hub 13 and a rotating portion 36 which is fastened to the first turbine stage 23 of drum 14. Between the stationary portion 35 and the rotating portion 36, support bearing 37 is provided. The metal ring 35, 36 is disposed coaxially to shaft 21 and has a larger diameter than the shaft 21 so that the gas can enter drum 14 between shaft 21 and the metal ring as well as between the metal ring and drum 14. With the aid of this metal ring 35, 36, the deflection force on the shaft 21 is reduced since it no longer must absorb the entire flexing moment. A portion of the flexing moment is transferred via the supporting bearing 37 to the longitudinal member 26 of the rotor hub 13, and simultaneously to the relatively rigid drum 14. A metal ring 35, 36 may also be disposed, together with a supporting bearing 37, at the outer end of a drum 14, in which case the transfer of the load is the most favorable. The number of revolutions, the load to be transferred, the diameter and the material employed are decisive for the design of the supporting bearing 37.

A further embodiment of the present invention is shown in FIG. 6 wherein the drums form the ends of the rotor blades. In this embodiment for aerodynamic reasons during cruising flight the diameter of the drums 14' decreases with decreasing distance from the rotor hub 13.

The drum 14' is here securely fastened to a shaft 43 which is rotatably mounted within the longitudinal or transverse member 26 or the rotor hub 13 and extends for a substantial distance therefrom. The mounting for the shaft 43 is provided by means of bearings 42 mounted in supporting struts 40 and 41, with the supporting struts 40 being located at substantially the end of the longitudinal member 26 and the supporting struts 41 being located a short distance therefrom within the member 26. Although only two groups of supporting struts 40, 41 have been illustrated, it is to be understood that additional support struts and bearings may be utilized if desired.

In order to drive or rotate the shaft 43 within the bearings 42 and thus the drum 14, a turbine stage 50 is securely fastened to the shaft 43 immediately following the supporting struts 40. Contrary to the embodiment of FIGS. 3 and 4 wherein the jet of gas 29 passed completely through the drum, according to this embodiment a short hollow member 44 is provided intermediate each drum l4 and the rotor hub 13. The intermediate member 44 is securely fastened to the end of the longitudinal member 26 of the hub 13 so that it does not rotate about the transverse rotor axis 15, Le. the axis of the shaft 43. This intermediate piece 44 is provided at one horizontal side thereof with guide blades or vanes 52 and nozzle-type discharge openings 45, whereas at the opposite side thereof there is disposed a sheet 46 which serves to deflect the gas jet toward the openings 45. Although in this embodiment the drums 14' need not be hollow, they are preferably made so in order to reduce the weight.

As with the embodiment of FIGS. 3 and 4, only one gas jet 29 is required to drive this lifting rotor. This stream or jet of gas 29 flows from the vertical member 25 through longitudinal member 26 of rotor hub 13, and the gas jet 29 passes then through the turbine stage 50 to drive drum 14' as indicated by arrow 51. After passing through turbine stage 50 the gas jet 29 enters the intennediate piece 44 and is deflected toward the nozzle-type discharge openings 45 by means of the sheet 46. Upon discharge of the gas jet, the resulting thrust drives the rotor hub 13 so that it rotates around axis 16 in the direction of arrow 31.

In this embodiment it can be seen that drums 14 need not and preferably donot have a constant diameter. It is rather possible to approach a shape which is more aerodynamically favorable during cruising. Retracting of the lifting rotors 12 as was suggested by the prior art teachings is not necessary so that the expensive retraction mechanism can be eliminated. The tapering shape of the drums 14' also results in the advantage of reduced weight for the rotor blades.

In order to reduce the aerodynamic drag of the lifting rotors during cruising flight when the required lift for the aircraft is being provided by the wings 11, the rotors 12 are stopped and maintained in a position wherein the rotor blades are parallel to the fuselage 10 of the aircraft. This may be done in any desired manner, for example by means of a detent mechanism.

Such a detent mechanism is shown in FIG. 7 wherein the wing profile is indicated by the reference numeral 53. Attached to the foot of the rotor hub 13 is a reinforcement ring 54 which is provided with a plurality of bores 55. Mounted below the ring 54 within the wing is a bolt 56 which is reciprocally mounted in a cylinder 57 which may for example be hydraulically operated. In order to guide the bolt 56, it is first passed through an opening in a further reinforcing ring disposed coaxially to the ring 54. When the rotor is to be locked in its desired position during cruising flight, the number of revolutions thereof is reduced and the bolt 56 is inserted into one of the bores 55 by energizing the cylinder 57. When the rotor is to be restarted, the bolt 56 is then merely retracted from the respective bore 55.

In order to facilitate proper alignment of the rotor prior to insertion of the bolt 56 into the bore 55, the reinforcement ring 54 is provided with teeth about its periphery which engage a gear 60 rotatably mounted on a servomotor 59 (e.g. an electroor hydraulic motor). Energization of the servomotor 59 will thus cause the rotor hub 13 to rotate whereby it can be aligned very accurately in the direction of air flow, i.e., parallel to the fuselage. This arrangement facilitates insertion of bolts 56 into one of bores 55 in a manner whereby no strong forces are built up in the bolt 56.

It is to be understood that although not illustrated, in each of the embodiments the guide vanes may be provided with a mechanism whereby the size of the nonle-shaped discharge openings may be varied or closed entirely. The closing of these openings during cruising flight results in a further improvement of the aerodynamic conditions.

ln an aircraft equipped with lifting rotors 12 according to the present invention, the control of the aircraft in the hovering state can be effected by means of the counterrevolving rotors, i.e., by changing the speed of rotor hubs 13 and drums 14. The lifting rotors according to the present invention result in good lift coefficients for an aircraft and thus, with a certain required lifting thrust, in small drums 14 and/or low peripheral speeds. This fact provides the additional advantage that the noise level is reduced.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

1 claim:

1. In an aircraft having at least one horizontal engine unit, and lifting rotors symmetrically disposed with respect to the fuselage for producing a lifting effect in an air current according to the Magnus effect, the improvement comprising:

a hollow rotor hub mounted for rotation about a first axis;

a plurality of rotor blades extending transversely from said rotor hub each of said blades including a drum rotating about the transverse axis of the respective one of said rotor blades;

at least one turbine stage mounted within said rotor for each rotor blade, each of said turbine stages being mounted for rotation about the transverse axis of the respective one of said blades and being coupled to the respective one of said drums for driving same when a stream of gas is passed therethrough in the axial direction;

means for directing a stream of gas through said rotor hub and each of said turbine stages; and

means including norzle shaped openings for discharging the stream of gas which has passed through the respective turbine stages from said rotor to produce a thrust which causes rotation of said rotor hub about said first axis.

2. The aircraft as defined in claim 11 wherein said aircraft is provided with two wings each of which has a lifting rotor at the end thereof.

3. The aircraft as defined in claim 2 wherein the required lifting force during takeoff and landing is produced by said lifting rotors, wherein each of said rotors has two rotor blades; and wherein means are provided for maintaining said lifting rotors, during cruising flight when the wings provide the required lift, in a stopped position wherein the rotor blades are parallel to said fuselage in order to provide a low aerodynamic drag. Y

4. The aircraft as defined in claim 1 wherein each of said drums is an axially mounted hollow tube, and wherein at least one of said turbine stages is mounted within each of said drums for rotation therewith.

5. The aircraft as defined in claim 4 wherein each of said drums has a constant diameter.

6. The aircraft as defined in claim 5 wherein a pair of said turbine stages are provided for each drum, one at each end thereof.

7. The aircraft as defined in claim d wherein the outer end of each of said rotor blades is provided with a stationary closing cap containing said nozzle-shaped discharge rneans.

ll. The aircraft as defined in claim 7 wherein each of said drums is mounted by means of bearings on a shaft which extends therethrough and which is securely fastened to said rotor head.

9. The aircraft as defined in claim 8 wherein said shaft is hollow and is utilized to conduct a stream of gas to said closing cap.

ill. The aircraft as defined in claim 1 wherein each of said drums is an axially mounted hollow tube whose diameter decreases with increasing distance from said first axis.

ill. The aircraft as defined in claim wherein said hollow member is securely fastened to said rotor hub for rotation therewith about said first axis, one of said hollow members being provided for each rotor blade and being positioned intermediate said rotor hub and the respective one of said rotating drums, and each of said members being provided with said discharge means; wherein each of said drums is mounted on a shaft which is rotatably supported within said member by means of bearings; and wherein one of said turbine stages is fastened to said shaft within said member and between said rotor hub and said discharge means.

112. The aircraft as defined in claim 1 wherein the rotor hub and the drums are driven by a stream of cold gas.

113. The aircraft as defined in claim I wherein said rotor hub and said drums are driven by a stream of hot gas.

M. The aircraft as defined in claim 1 wherein said rotor hub and said drums are driven by a mixed stream of hot and cold 115. The aircraft as defined in claim 2, wherein said means for maintaining said lifting rotor in a stopped position during cruising flight includes a detent device provided at each outer end of said wings for engaging said lifting rotors.

16. The aircraft as defined in claim 7 including means mounted within said rotor for enhancing the flow of said stream of gas through said hub and said drum and for distributing the bending moment on said rotor blades, said means comprising a metal ring mounted coaxially with said shaft and having a diameter greater than said shaft, said ring having a first portion securely fastened to said rotor hub and a second portion fastened to said drum for rotation therewith, and bearing means engaging the juxtaposed surfaces of said first and second portions of said ring. 

1. In an aircraft having at least one horizontal engine unit, and lifting rotors symmetrically disposed with respect to the fuselage for producing a lifting effect in an air current according to the Magnus effect, the improvement comprising: a hollow rotor hub mounted for rotation about a first axis; a plurality of rotor blades extending transversely from said rotor hub each of said blades including a drum rotating about the transverse axis of the respective one of said rotor blades; at least one turbine stage mounted within said rotor for each rotor blade, each of said turbine stages being mounted for rotation about the transverse axis of the respective one of said blades and being coupled to the respective one of said drums for driving same when a stream of gas is passed therethrough in the axial direction; means for directing a stream of gas through said rotor hub and each of said turbine stages; and means including nozzle shaped openings for discharging the stream of gas which has passed through the respective turbine stages from said rotor to produce a thrust which causes rotation of said rotor hub about said first axis.
 2. The aircraft as defined in claim 1 wherein said aircraft is provided with two wings each of which has a lifting rotor at the end thereof.
 3. The aircraft as defined in claim 2 wherein the required lifting force during takeoff and landing is produced by said lifting rotors, wherein each of said rotors has two rotor blades; and wherein means are provided for maintaining said lifting rotors, during cruising flight when the wings provide the required lift, in a stopped position wherein the rotor blades are parallel to said fuselage in order to provide a low aerodynamic drag.
 4. The aircraft as defined in claim 1 wherein each of said drums is an axially mounted hollow tube, and wherein at least one of said turbine stages is mounted within each of said drums for rotation therewith.
 5. The aircraft as defined in claim 4 wherein each of said drums has a constant diameter.
 6. The aircraft as defined in claim 5 wherein a pair of said turbine stages are provided for each drum, one at each end thereof.
 7. The aircraft as defined in claim 4 wherein the outer end of each of said rotor blades is provided with a stationary closing cap containing said nozzle-shaped discharge means.
 8. The aircraft as defined in claim 7 wherein each of said drums is mounted by means of bearings on a shaft which extends therethrough and which is securely fastened to said rotor head.
 9. The aircraft as defined in claim 8 wherein said shaft is hollow and is utilized to conduct a stream of gas to said closing cap.
 10. The aircraft as defined in claim 1 wherein each of said drums is an axially mounted hollow tube whose diameter decreases with increasing distance from said first axis.
 11. The aircraft as defined in claim 10 wherein said hollow member is securely fastened to said rotor hub for rotation therewith about said first axis, one of said hollow members being provided for each rotor blade and being positioned intermediate said rotor hub and the respective one of said rotating drums, and each of said members being provided with said discharge means; wherein each of said drums is mounted on a shaft which is rotatably supported within said member by means of bearings; and wherein one of said turbine stages is fastened to said shaft within said member and between said rotor hub and said discharge means.
 12. The aircraft as defined in claim 1 wherein the rotor hub and the drums are driven by a stream of cold gas.
 13. The aircraft as defined in claim 1 wherein said rotor hub and said drums are driven by a stream of hot gas.
 14. The aircraft as defined in claim 1 wherein said rotor hub and said drums are driven by a mixed stream of hot and cold gas.
 15. The aircraft as defined in claim 2, wherein said means for maintaining said lifting rotor in a stopped position during cruising flight includes a detent device provided at each outer end of said wings for engaging said lifting rotors.
 16. The aircraft as defined in claim 7 including means mounted within said rotor for enhancing the flow of said stream of gas through said hub and said drum and for distributing the bending moment on said rotor blades, said means comprising a metal ring mounted coaxially with said shaft and having a diameter greater than said shaft, said ring having a first portion securely fastened to said rotor hub and a second portion fastened to said drum for rotation therewith, and bearing means engaging the juxtaposed surfaces of said first and second portions of said ring. 